592 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [126] 



constantly supjilied with fresb water, and often examine the i^onds with 

 the view to ascertain whether the supply is sufficient. It would be a 

 great mistake to wait till the fish begin to ai)pear at the air-holes gasp- 

 ing for breath. 



It is a very general opinion that in severe winters the fish are apt to 

 perish owing to the lack of air-holes, and the consequent lack of fresh 

 air. I deem it proper, therefore, to give a different view which is enter- 

 tained by Von Eeider. lie says: "If the pond is deep enough, the 

 water flowing into it will prevent it from freezing. If the water flows 

 out freely, the water in the pond is kept in constant motion and is 

 therefore not so apt to freeze. The fresh water will also introduce fresh 

 air into the pond, and there is no danger wiiatever tbat the water in the 

 pond will become vitiated. Even if the pond is covered with ice, and 

 the supply of fresh air from above is cut off", the water which flows in 

 and out under the ice will keep up a constant current of fresh air, and 

 prevent a vitiation of the water. If a winter pond, therefore, has a well- 

 regulated sui)i>ly of water, no harm will be done by a covering of ice 

 even if the snow lies deep on it ; on the contrary, it will keepotf the frost 

 from the water below, and the fish will, in the constantly running water, 

 which owing to its cover of ice and snow is kept at a pleasant tempera- 

 ture, always be safe and healthy. All that has to be done in a very se- 

 vere winter is to keep the ice from stopping or impeding the flo\^'of the 

 water. It will rarely freeze if kept in constant motion, but it will be 

 well to give a little aid by breaking holes in the ice at the places where 

 the w;iter flows in and out. It is unnecessary, and may even be iiijuri- 

 ous, to make air-holes in tlie ice, as the cover of ice and snow is to pre- 

 vent the fiost frotn entering the depths. If. however, extremely cold 

 weather slnndd continue for a considerable length of time, it may hap- 

 pen that the water flows over the ice, and in that case it will become 

 necessary to make holes in the ice, but only in those places where the 

 water flows in and out. Here the ice should be removed, so the Avater 

 can resume its usual course." Von lleider goes on to say that "the 

 above statement satisfactorily settles the question whether it is useful 

 and proper to break the ice in winter ponds. All that is needed is to 

 secure ready access to the pond for the fresh water and to facilitate its 

 outflow."* • 



Deliust is also inclined to think that there is little use in making 

 air-holes in tlie ice for the purpose of a constant contact between air 

 and water, because, as he says, the existence of the tish is already en- 

 dangered when they seek the air-holes. lie thinks that even if the pond 

 is frozen and the flow of water is stoi)ped, the fish will, at any rate iu 

 large and deep ponds, be fully protected against the danger of freezing, 

 and that only in small ponds are they apt to become languid and seek 

 the holes to get a breath of fresh air ; and if they do not succeed in this, 



* Von Reider, Das Game der Fischerei, 1825. 

 t Delias, Ttichwirtkschaft, p. 35. 



